A Q-band (34 GHz) EPR spectrometer bridge and cryostat is designed to have the following properties: tunability over a wide dynamic range, high sensitivity, and undetectable manganese impurity signals down to the helium lambda point, with the cavity in gas or immersed in liquid He. Provision for optical irradiation of sample in situ through the cryostat top flange. Suitable for wide range of metalloprotein or radical samples for biomedical research. Design is joint effort between Bruker Instruments and the IERC, with Bruker being responsible for construction and performance certification.